Recently, there have been advances in the development of techniques for increasing as much as possible the amount by which the opening in a roof opens in sunroof apparatuses for vehicles. In systems for opening and closing the opening by means of one sunroof panel, there are limits to increasing the size of the opening. Systems for segmenting the sunroof panel have been considered to overcome these limits. However, this is not the best recourse because the configuration becomes complicated if the panel is segmented excessively. To this end, a technique of a system for longitudinally halving the sunroof panel into a front panel and a rear panel is proposed in, for example, Japanese Utility Model Publication No. 04-26254 (JP-U 04-26254 B) and Japanese Patent Application Laid-Open Publication No. 2002-103977 (JP 2002-103977 A).
In the sunroof apparatus disclosed in JP-U 04-26254 B, a front panel and a rear panel are opened and closed separately by a motor via a wire cable. The operation of the rear panel is in indirect engagement with the operation of the front panel via the wire cable. The motor opens the front and rear panels by pulling the wire cable, and closes the front and rear panels by pushing the wire cable.
More specifically, when in a fully closed state, the front and rear panels are opened in the following procedure. First, the rear end of the front panel is inclined upward (i.e., tilted up). Next, the front panel retracts along the outside surface of the roof, and opens to a half-open position. Next, the rear panel is lowered below the inside surface of the roof. Lastly, while the rear panel retracts along the inside surface of the roof and opens to a fully open position, the front panel retracts along the outside surface of the roof and opens to a fully open position.
The vehicular sunroof apparatus disclosed in JP 2002-103977 A is arranged similarly to the sunroof apparatus disclosed in JP-U 04-26254 B.
As described above, a front panel and a rear panel are opened and closed separately via a wire cable. That is, the rear panel is arranged to act in unison with or in an interlocked relation to the front panel via the wire cable. However, the wire cable is liable to encounter sagging as a result of aging. Due to such sagging, the front and rear panels encounter positional discrepancies. If such positional discrepancies are left unattended, timed actions of the front and rear panels will fail. It is quite important to maintain the timing of action between the front and rear panels in an appropriate state for a long period of time because the timing of action will have a large influence on the action of the vehicular sunroof apparatus.
To this end, one may propose adding to the apparatus an adjusting mechanism for adjusting discrepancies in timed operations of associated members, which may arise due to flexure of associated a wire cable. However, this is not advantageous in that it makes the sunroof apparatus more complex in construction and requires periodical adjustment operations
One may also propose replacing the wire cable with another suitable transmission member such as a bar-shaped transmission member. However, it is difficult to arrange such a bar-shaped non-flexible transmission member to extend from the motor to the front and rear panels. In addition, this will make the sunroof arrangement complex in construction and hence is unacceptable.
Again, one may propose directly connecting the front panel with the rear panel, without using a wire cable. However, since the front and rear panels move and stop at largely different timings, simply connecting the two panels is insufficient. For connecting the two panels, due considerations should be given to different timings at which the two panels move and stop as well as to measures for keeping the unison operations of the front and rear panels for a prolonged period of time.
Consequently, there is a demand for a technique whereby appropriate unison operations of the front and rear panels are provided for a prolonged period of time.